Sentry integration (#13)

* Sentry integration

* Introduce a more generic CIRRUS_SENTRY_TAGS

* Revert switching to nightly toolchain

.cirrus.yml

@@ -23,5 +23,5 @@ task:
   install_goreleaser_script:
     - brew install go goreleaser/tap/goreleaser-pro
   build_script:
-    - cargo build --release
+    - cargo build --profile release-with-debug
   release_script: goreleaser

.goreleaser.yml

@@ -7,7 +7,7 @@ builds:
     goarch:
       - arm64
     prebuilt:
-      path: target/release/softnet
+      path: "target/release-with-debug/softnet"
 
 archives:
   - id: binary

Cargo.toml

@@ -7,6 +7,10 @@ edition = "2021"
 [lib]
 path = "lib/mod.rs"
 
+[profile.release-with-debug]
+inherits = "release"
+debug = true
+
 [dependencies]
 smoltcp = "0.8.1"
 libc = "0.2.126"
@@ -16,8 +20,10 @@ vmnet = "0.1.1"
 clap = { version = "3.1.18", features = ["derive"] }
 mac_address = "1.1.3"
 privdrop = "0.5.2"
-thiserror = "1.0.31"
+anyhow = { version = "1.0.66", features = ["backtrace"] }
 ip_network = "0.4.1"
 users = "0.11.0"
 system-configuration = "0.5.0"
 num_enum = "0.5.7"
+sentry = "0.29.1"
+sentry-anyhow = { version = "0.29.1", features = ["backtrace"] }

README.md

@@ -20,12 +20,12 @@ And assumes that:
 
 ## Installing
 
-For proper functioning Softnet binary requires two things:
+For proper functioning, Softnet binary requires two things:
 
-* a [SUID-bit](https://en.wikipedia.org/wiki/Setuid#SUID) is set on the binary or [passwordless sudo](https://serverfault.com/questions/160581/how-to-setup-passwordless-sudo-on-linux) is enabled, which effectively gives the binary `root` privileges
-  * this is needed in order to create [`vmnet.framework`](https://developer.apple.com/documentation/vmnet) interface and perform DHCP-related tweaks
+* a [SUID-bit](https://en.wikipedia.org/wiki/Setuid#SUID) to be set on the binary or a [passwordless sudo](https://serverfault.com/questions/160581/how-to-setup-passwordless-sudo-on-linux) to be configured, which effectively gives the binary `root` privileges
+  * these privileges are needed to create [`vmnet.framework`](https://developer.apple.com/documentation/vmnet) interface and perform DHCP-related system tweaks
   * the privileges will be dropped automatically to that of the calling user (or those represented by the `--user` and `--group` command-line arguments) once all of the initialization is completed
-* the binary is available in `PATH`
+* the binary to be available in `PATH`
   * so that the Tart will be able to find it
 
 ## Running

lib/host.rs

@@ -1,4 +1,4 @@
-use crate::{Error, Result};
+use anyhow::{anyhow, Context, Result};
 use std::net::Ipv4Addr;
 use std::os::unix::io::{AsRawFd, RawFd};
 use std::os::unix::net::UnixDatagram;
@@ -27,27 +27,23 @@ impl Host {
                 ..Default::default()
             },
         )
-        .map_err(|err| Error::VmnetFailed { source: err })?;
+        .context("failed to initialize vmnet interface")?;
 
         // Retrieve first IP (gateway) used for this interface
-        let gateway_ip = match interface.parameters().get(ParameterKind::StartAddress) {
-            Some(Parameter::StartAddress(gateway_ip)) => gateway_ip,
-            _ => return Err(Error::VmnetUnexpected),
+        let Some(Parameter::StartAddress(gateway_ip)) = interface.parameters().get(ParameterKind::StartAddress) else {
+            return Err(anyhow!("failed to retrieve vmnet's interface start address"));
         };
-        let gateway_ip = Ipv4Addr::from_str(&gateway_ip).map_err(|_| Error::VmnetUnexpected)?;
+        let gateway_ip = Ipv4Addr::from_str(&gateway_ip)
+            .context("failed to parse vmnet's interface start address")?;
 
         // Retrieve max packet size for this interface
-        let max_packet_size = match interface.parameters().get(ParameterKind::MaxPacketSize) {
-            Some(Parameter::MaxPacketSize(max_packet_size)) => max_packet_size,
-            _ => return Err(Error::VmnetUnexpected),
+        let Some(Parameter::MaxPacketSize(max_packet_size)) = interface.parameters().get(ParameterKind::MaxPacketSize) else {
+            return Err(anyhow!("failed to retrieve vmnet's interface max packet size"));
         };
 
         // Set up a socketpair() to emulate polling of the vmnet interface
-        let (new_packets_tx, new_packets_rx) =
-            UnixDatagram::pair().map_err(|err| Error::InitFailed { source: err.into() })?;
-        new_packets_rx
-            .set_nonblocking(true)
-            .map_err(|err| Error::InitFailed { source: err.into() })?;
+        let (new_packets_tx, new_packets_rx) = UnixDatagram::pair()?;
+        new_packets_rx.set_nonblocking(true)?;
 
         let (callback_can_continue_tx, callback_can_continue_rx) = sync_channel(0);
 
@@ -64,7 +60,7 @@ impl Host {
                 // [1]: https://en.wikipedia.org/wiki/Blocks_(C_language_extension)
                 callback_can_continue_rx.recv().unwrap();
             })
-            .map_err(|err| Error::VmnetFailed { source: err })?;
+            .context("failed to set vmnet interface's event callback")?;
 
         Ok(Host {
             interface,
@@ -104,14 +100,14 @@ impl Host {
         // First make sure our callback won't be scheduled again after it finishes
         self.interface
             .clear_event_callback()
-            .map_err(|err| Error::VmnetFailed { source: err })?;
+            .context("failed to clear vmnet interface's event callback")?;
 
         // Now let the callback finish
-        self.callback_can_continue_tx.send(()).unwrap();
+        let _ = self.callback_can_continue_tx.send(());
 
         self.interface
             .finalize()
-            .map_err(|err| Error::VmnetFailed { source: err })?;
+            .context("failed to finalize vmnet's interface")?;
 
         self.finalized = true;
 

lib/mod.rs

@@ -3,28 +3,3 @@ mod host;
 mod poller;
 pub mod proxy;
 mod vm;
-
-use thiserror::Error;
-
-#[derive(Error, Debug)]
-pub enum Error {
-    #[error("initialization failed")]
-    InitFailed { source: Box<dyn std::error::Error> },
-
-    #[error("failed to poll")]
-    PollFailed { source: std::io::Error },
-
-    #[error("vmnet failed")]
-    VmnetFailed { source: vmnet::Error },
-
-    #[error("vmnet returned unexpected data")]
-    VmnetUnexpected,
-
-    #[error("failed to do I/O on VM socket")]
-    VMIOFailed { source: std::io::Error },
-
-    #[error("failed to do I/O on host socket")]
-    HostIOFailed { source: vmnet::Error },
-}
-
-pub type Result<T> = std::result::Result<T, Error>;

lib/poller.rs

@@ -1,4 +1,4 @@
-use crate::{Error, Result};
+use anyhow::Result;
 use num_enum::IntoPrimitive;
 use std::os::unix::io::RawFd;
 use std::time::Duration;
@@ -19,8 +19,7 @@ enum EventKey {
 
 impl Poller {
     pub fn new(vm_fd: RawFd, host_fd: RawFd) -> Result<Poller> {
-        let poller =
-            polling::Poller::new().map_err(|err| Error::InitFailed { source: err.into() })?;
+        let poller = polling::Poller::new()?;
 
         Ok(Poller {
             poller,
@@ -31,13 +30,9 @@ impl Poller {
     }
 
     pub fn arm(&self) -> Result<()> {
+        self.poller.add(self.vm_fd as RawFd, self.vm_interest())?;
         self.poller
-            .add(self.vm_fd as RawFd, self.vm_interest())
-            .map_err(|err| Error::PollFailed { source: err })?;
-
-        self.poller
-            .add(self.host_fd as RawFd, self.host_interest())
-            .map_err(|err| Error::PollFailed { source: err })?;
+            .add(self.host_fd as RawFd, self.host_interest())?;
 
         Ok(())
     }
@@ -46,19 +41,16 @@ impl Poller {
         self.events.clear();
 
         self.poller
-            .modify(self.vm_fd as RawFd, self.vm_interest())
-            .map_err(|err| Error::PollFailed { source: err })?;
+            .modify(self.vm_fd as RawFd, self.vm_interest())?;
         self.poller
-            .modify(self.host_fd as RawFd, self.host_interest())
-            .map_err(|err| Error::PollFailed { source: err })?;
+            .modify(self.host_fd as RawFd, self.host_interest())?;
 
         Ok(())
     }
 
     pub fn wait(&mut self) -> Result<(bool, bool)> {
         self.poller
-            .wait(&mut self.events, Some(Duration::from_millis(100)))
-            .map_err(|err| Error::PollFailed { source: err })?;
+            .wait(&mut self.events, Some(Duration::from_millis(100)))?;
 
         let vm_readable = self.events.iter().any(|ev| ev.key == EventKey::VM.into());
         let host_readable = self.events.iter().any(|ev| ev.key == EventKey::Host.into());

lib/proxy/host.rs

@@ -1,6 +1,6 @@
 use crate::proxy::udp_packet_helper::UdpPacketHelper;
 use crate::proxy::Proxy;
-use crate::{Error, Result};
+use anyhow::{Context, Result};
 use smoltcp::wire::{EthernetFrame, EthernetProtocol, Ipv4Packet, UdpPacket};
 
 impl Proxy {
@@ -12,12 +12,14 @@ impl Proxy {
 
         // Snoop bootpd(8) replies from the host to
         // figure out the IP assigned to the VM
-        self.snoop(frame);
+        if frame.dst_addr() == self.vm_mac_address {
+            self.snoop(frame);
+        }
 
         self.vm
             .write(frame.as_ref())
             .map(|_| ())
-            .map_err(|err| Error::VMIOFailed { source: err })
+            .context("failed to write to the VM")
     }
 
     fn allowed_from_host(&mut self, frame: &EthernetFrame<&[u8]>) -> Option<()> {

lib/proxy/mod.rs

@@ -6,8 +6,7 @@ use crate::dhcp_snooper::DhcpSnooper;
 use crate::host::Host;
 use crate::poller::Poller;
 use crate::vm::VM;
-use crate::Error;
-use crate::Result;
+use anyhow::Result;
 use mac_address::MacAddress;
 use smoltcp::wire::EthernetFrame;
 use std::io::ErrorKind;
@@ -69,7 +68,7 @@ impl Proxy {
                         return Ok(());
                     }
 
-                    return Err(Error::VMIOFailed { source: err });
+                    return Err(err.into());
                 }
             }
         }
@@ -88,7 +87,7 @@ impl Proxy {
                         return Ok(());
                     }
 
-                    return Err(Error::HostIOFailed { source: err });
+                    return Err(err.into());
                 }
             }
         }

lib/proxy/vm.rs

@@ -1,6 +1,7 @@
 use crate::proxy::udp_packet_helper::UdpPacketHelper;
 use crate::proxy::Proxy;
-use crate::{Error, Result};
+use anyhow::Context;
+use anyhow::Result;
 use smoltcp::wire::{
     ArpPacket, EthernetFrame, EthernetProtocol, IpProtocol, Ipv4Packet, UdpPacket,
 };
@@ -16,7 +17,7 @@ impl Proxy {
         self.host
             .write(frame.as_ref())
             .map(|_| ())
-            .map_err(|err| Error::HostIOFailed { source: err })
+            .context("failed to write to the host")
     }
 
     fn allowed_from_vm(&self, frame: &EthernetFrame<&[u8]>) -> Option<()> {

lib/vm.rs

@@ -1,4 +1,4 @@
-use crate::{Error, Result};
+use anyhow::Result;
 use std::os::unix::io::{AsRawFd, FromRawFd, RawFd};
 use std::os::unix::net::UnixDatagram;
 
@@ -9,8 +9,7 @@ pub struct VM {
 impl VM {
     pub fn new(vm_fd: RawFd) -> Result<VM> {
         let sock = unsafe { UnixDatagram::from_raw_fd(vm_fd) };
-        sock.set_nonblocking(true)
-            .map_err(|err| Error::InitFailed { source: err.into() })?;
+        sock.set_nonblocking(true)?;
 
         Ok(VM { sock })
     }

src/main.rs

@@ -1,10 +1,12 @@
+use anyhow::{anyhow, Context};
 use clap::Parser;
 use privdrop::PrivDrop;
 use softnet::proxy::Proxy;
+use std::env;
 use std::os::raw::c_int;
 use std::os::unix::io::RawFd;
 use std::os::unix::process::CommandExt;
-use std::process::Command;
+use std::process::{Command, ExitCode};
 use system_configuration::core_foundation::base::TCFType;
 use system_configuration::core_foundation::dictionary::CFDictionary;
 use system_configuration::core_foundation::number::CFNumber;
@@ -27,7 +29,7 @@ struct Args {
     #[clap(
         long,
         help = "set bootpd(8) lease time to this value (in seconds) before starting the VM",
-        default_value_t = 60
+        default_value_t = 600
     )]
     bootpd_lease_time: u32,
 
@@ -37,24 +39,49 @@ struct Args {
     #[clap(long, help = "group name to drop privileges to")]
     group: Option<String>,
 
-    #[clap(long, hide=true)]
+    #[clap(long, hide = true)]
     sudo_escalation_probing: bool,
 
-    #[clap(long, hide=true)]
+    #[clap(long, hide = true)]
     sudo_escalation_done: bool,
 }
 
-fn main() {
-    if let Err(err) = try_main() {
-        match err.source() {
-            Some(source) => eprintln!("{}: {}", err, source),
-            None => eprintln!("{}", err),
+fn main() -> ExitCode {
+    // Enable backtraces by default
+    if env::var("RUST_BACKTRACE").is_err() {
+        env::set_var("RUST_BACKTRACE", "1");
+    }
+
+    // Initialize Sentry
+    let _sentry = sentry::init(sentry::ClientOptions {
+        ..Default::default()
+    });
+
+    // Enrich future events with Cirrus CI-specific tags
+    if let Ok(tags) = env::var("CIRRUS_SENTRY_TAGS") {
+        sentry::configure_scope(|scope| {
+            for (key, value) in tags.split(",").map(|tag| tag.split_once("=")).flatten() {
+                scope.set_tag(key, value);
+            }
+        });
+    }
+
+    match try_main() {
+        Ok(_) => ExitCode::SUCCESS,
+        Err(err) => {
+            // Print the error into stderr
+            let causes: Vec<String> = err.chain().map(|x| x.to_string()).collect();
+            eprintln!("{}", causes.join(": "));
+
+            // Capture the error into Sentry
+            sentry_anyhow::capture_anyhow(&err);
+
+            ExitCode::FAILURE
         }
-        std::process::exit(1);
     }
 }
 
-fn try_main() -> Result<(), Box<dyn std::error::Error>> {
+fn try_main() -> anyhow::Result<()> {
     let args: Args = Args::parse();
 
     // No need to run anything, just return
@@ -66,11 +93,11 @@ fn try_main() -> Result<(), Box<dyn std::error::Error>> {
 
     // Retrieve real (not effective) user and group names
     let current_user_name = get_current_username()
-        .ok_or("failed to resolve real user name")?
+        .ok_or(anyhow!("failed to resolve real user name"))?
         .to_string_lossy()
         .to_string();
     let current_group_name = get_current_groupname()
-        .ok_or("failed to resolve real group name")?
+        .ok_or(anyhow!("failed to resolve real group name"))?
         .to_string_lossy()
         .to_string();
 
@@ -81,7 +108,8 @@ fn try_main() -> Result<(), Box<dyn std::error::Error>> {
             let args = std::env::args().skip(1);
 
             let _ = Command::new("sudo")
-                .arg("-n")
+                .arg("--non-interactive")
+                .arg("--preserve-env=SENTRY_DSN,CIRRUS_SENTRY_TAGS")
                 .arg(&exe)
                 .args(args)
                 .arg("--sudo-escalation-done")
@@ -92,14 +120,17 @@ fn try_main() -> Result<(), Box<dyn std::error::Error>> {
                 .exec();
         }
 
-        return Err("root privileges are required to run and passwordless sudo was not available".into());
+        return Err(anyhow!(
+            "root privileges are required to run and passwordless sudo was not available"
+        ));
     }
 
     // Set bootpd(8) min/max lease time while still having the root privileges
     set_bootpd_lease_time(args.bootpd_lease_time);
 
     // Initialize the proxy while still having the root privileges
-    let mut proxy = Proxy::new(args.vm_fd as RawFd, args.vm_mac_address)?;
+    let mut proxy = Proxy::new(args.vm_fd as RawFd, args.vm_mac_address)
+        .context("failed to initialize proxy")?;
 
     // Drop effective privileges to the user
     // and group which have had invoked us
@@ -107,10 +138,10 @@ fn try_main() -> Result<(), Box<dyn std::error::Error>> {
         .user(args.user.unwrap_or(current_user_name))
         .group(args.group.unwrap_or(current_group_name))
         .apply()
-        .map_err(|err| format!("failed to drop privileges: {}", err))?;
+        .context("failed to drop privileges")?;
 
     // Run proxy
-    proxy.run().map_err(|err| err.into())
+    proxy.run()
 }
 
 fn sudo_escalation_works() -> bool {